An Organic Light Emitting Diode (OLED) has attracted the most attention in a research field for a flat panel display recently. As compared with a liquid crystal display, the OLED has advantages of low power consumption, low manufacture cost, self-illumination, wide angle of view, rapid response speed, etc. Currently, the OLED has replaced a traditional Liquid Crystal Display (LCD) screen gradually in the display field such as mobile phone, PDA, digital camera and the like. A design of a pixel driving circuit is a core technique in an OLED display and has fatal research significance.
Unlike a Thin Film Transistor (TFT)-LCD which controls its brightness with a stable voltage, the OLED is driven by current and needs a stable current to control the light emitting.
Because of processes and aging of devices or other reasons, in an existing 2T1C driving circuit (comprising two thin film transistors and one capacitor), threshold voltages of driving TFTs at respective pixel points are not uniform, which causes variances in the currents flowing through the OLEDs of corresponding pixel points and in turn leads to a non-uniformity in the display brightness, such that a display effect of an entire image is affected.
Generally, one pixel circuit usually corresponds to one pixel, each pixel circuit at least comprises one data voltage line, one operating voltage line and a plurality of scan signal lines, such that a corresponding manufacture process is complex, which is disadvantageous for reducing a pixel pitch.